The relationship between the collision and the granite is a problem of common concern among geologists, nevertheless, many misunderstandings exist in the current study. This paper argues that collision is a tectonic event in shallow crust and hence does not belong to the category of tectonic setting. Granite is probably formed by the partial melting of the bottom of the lower crust. The formation of granite needs heat, and the heat mainly comes from the mantle. Collision can't produce granite. The differences of granite geochemistry between syn-collision and post-collision are related to the change of crust thickness caused by collision. So, the discrimination diagrams of tectonic settings, if they contain collision, are completely wrong.